Waste water immersion probes are used for the detection of various parameters in waste water. Examples of these probes are turbidity sensors or solid matter sensors, ultrasonic sludge blanket probes, UV or nitrate probe, etc. In each of these immersion probes, a sensor is arranged in the housing that, through a sensor window in or at the housing, measures one of the mentioned parameters in the waste water outside the housing. Accretions on the outside of the sensor window can corrupt or even make the sensor measurements impossible.
From DE 4 233 218 A1, a waste water immersion probe for turbidity measurement is known. The sensor is an optical sensor that receives light through an optical window. The sensor window can be cleaned by a wiper sweeping across the outer side of the sensor window. The wiper is driven by an electric drive motor arranged in the housing. The drive motor and the wiper are connected via a shaft passing through an opening in the housing. Thus, the shaft has to be sealed by means of a shaft sealing. Experience has shown that shaft sealings only have a limited sealing effect or seal reliably only for a limited time. In the event of a leak, liquid enters the housing so that the housing is eventually flooded and the components therein are destroyed.